1. Field of the Invention
This invention relates to a new heat exchanger system and to a new fuel control system for such a heat exchanger system as well as to new methods of making such a heat exchanger system and such a fuel control system.
2. Prior Art Statement
It is known to provide a fuel control system for a heat exchanger system that comprises a thermostat, burner means, and electrically operated igniter means for igniting fuel that issues from the burner means, the fuel control system comprising electrical circuit means that comprises an ignition trial portion for operating the igniter means, a flame sense control portion for operating the burner means, and a timer portion adapted on each cycle of closing of the thermostat and before the next opening thereof to cause the ignition trial portion to tend to operate the igniter means for a first certain period of trial time, said flame sense control portion being adapted to terminate the operation of the igniter means during the first certain period of trial time if the flame sense portion senses that fuel issuing from the burner means has been ignited, the timer portion being adapted to terminate the operation of the igniter means upon the termination of the first certain period of trial time if no flames appear at the burner means and to provide a first certain period of wait time before causing the ignition trial portion to tend to operate the igniter means for a second certain period of trial time during that cycle, the flame sense control portion being adapted to terminate the operation of the igniter means during the second certain period of trial time if the flame sense control portion senses that fuel issuing from the burner means has been ignited, the timer portion comprising a counter having a plurality of outputs and a timer that clocks the output of the counter on each discharge of the timer, a capacitor for causing the timer to discharge and discharge the capacitor to a discharged condition thereof upon each charging of the capacitor to a certain voltage, trial time resistor means, and wait time resistor means, the counter when clocked to a first output thereof by the timer being adapted to place the trial time resistor means and the capacitor in series at the start of the first trial time period so that the trial time resistor means determines the time period the capacitor charges from its discharged condition to the certain voltage thereof and that time period comprises the first certain trial time period, the counter when clocked to a second output thereof by the timer being adapted to place the wait time resistor means and the capacitor in series at the start of the wait time period so that the wait time resistor means determines the time period the capacitor charges from the discharged condition thereof to the certain voltage thereof and that time period comprises the wait time period, the counter when clocked to a third output thereof by the timer being adapted to place the trial time resistor means and the capacitor in series at the start of the second trial time period so that the trial time resistor means determines the time period the capacitor charges from its discharged condition to the certain voltage thereof and that time period comprises the second certain trial time period. For example, see the U.S. Pat. to Geary, No. 5,141,431.
For similar fuel control systems, see the U.S. Pat. to Geary, Nos. 4,836,770; 4,856,983; 4,971,549 and 4,976,605.
Also see Chapter 8, pages 15514 173 of the book, IC Timer Hand Book With One Hundred Projects And Experiments by Joseph J. Carr, published by Tab Books Inc. in 1981 for various applications of such a counter.